This invention relates generally to the formation of a composite helicopter blade, and more specifically pertains to the means and method for forming a structurally reinforced blade assembly incorporating reduced metallic or other weight enhancing structures within the composite form.
The helicopter has become very much in vogue over the past few decades as a very necessary instrument in the military arsenal. In addition, it has gained widespread acceptance in the field of transportation and surveillance. The early designs for this airborne craft more generally were used for transporting a variety of personnel and equipment, many of the contemporary uses for the aircraft include only the conveyance of one or two occupants for a short duration of time. For example, the helicopter may now be used for reconnaissance in the military field, or for carry only a pilot and an observer, as frequently used for traffic forecasting around the urban centers. As a result, it has become desirable to significantly reduce the weight of the craft. Included in such reduction has been the emphasis upon constructing the rotor blade from light weight materials other than metals. As an example, as seen in the U.S. Pat. to Brunsch, No. 3,713,753, the airfoil for the helicopter rotor blade is formed from a reinforced fiber that is laminated upon a mandrel into the shape of a helicopter blade. And, another patent to the same inventor, U.S. Pat. No. 3,476,484, discloses a rotor blade having fiber reinforced plastic strands that extend in a longitudinal direction along the blade so as to reinforced the blade, and to strengthen the same in the position of its root end.
Still another prior art patent, U.S. Pat. No. 3,754,840, to the inventor Zincone, discloses a composite helicopter rotor and blade which is built around a selectively fabricated structural spar. The invention includes a central filler member formed from a plurality of fibers, and teaches the method of developing strength through the capturing of metallic components within its laminae.
While these prior art disclosures are significant for showing various forms of helicopter blade assemblies, formed from lighter weight materials, and even having inherent substantially enhanced strength, the prior art further discloses the integration of metallic components within the blade assembly in order to attain the strength desired for their specific fabrications.
The primary object of the current invention is to provide a composite helicopter rotor blade that includes provision for attachment of the blade to the rotary head through a multiple, all composite, arrangement of inherent lugs, without incorporating captured metallic parts, such as shown in the prior art, such as increases the weight of earlier style blades, reduces their reliability, and due to their material make up are subjected to environmental and stress corrosions during service.
A further object of this invention is the conception of the fabrication of a helicopter blade, and its spar root end, through the use of preimpregnated tapes of fiber, such as fiberglass, or other plastic, adhered with an advanced epoxy or other resin and which is more suitable to automated lay up and production than can be attained from the dry fiber type assemblies as used in the prior art that subsequently apply an application of a wet epoxy resin after the form emplacement of its patterned fiber components.
Another object of this invention is the provision of particularly and patterned arranged reinforcing tapes into the configuration of a helicopter blade assembly so as to provide integral reinforcement between the proximate leading upper and lower edges of the formed blade with its securement to the rotary head at the helicopter attaching root assembly.
A further object of this invention is the provision of a form of arranged fiber reinforced components that are die compressed and cured into their precise final configuration of the desired blade assembly.
Yet another object of this invention is the disclosure of a tooling concept for forming a significantly reinforced helicopter blade.
Still a further objective of this invention is the provision of tooling and their sequential usage for furnishing degrees of pressurization and heat for effecting precise initial formation and subsequent setting of a completely nonmetallic formed helicopter blade assembly.
These and other objects will become more apparent to those skilled in the art upon reviewing the summary of this invention, and upon undertaking a study of its preferred embodiment in view of its drawings.